1. Field of the Invention
The present invention relates to an airbag for ensuring the safety of an occupant in the event of collision of the vehicle or the like, and an airbag device that uses the same.
2. Description of the Related Art
There have heretofore been known airbag devices whereby an inflator activates in the event of an emergency, such as collision or rollover of the vehicle, and an airbag formed into a bag inflates and deploys from a folded state by pressurized gas jetted from this inflator, restraining the occupant.
The airbag used in the airbag device comprises an airbag main body formed into a bag so as to comprise at least a first panel and a second panel in the inflated and deployed state, and a vent hole formed on the second panel. When an occupant contacts the inflated and deployed airbag main body, the pressurized gas is made to discharge from the interior of the airbag main body via this vent hole. With this arrangement, it is possible to smoothly receive and hold the occupant by the airbag main body.
In recent years, there have been proposed airbags configured so that the vent hole is in a closed or slightly opening degree until the internal pressure of the airbag main body reaches a predetermined value or higher, and then is in an open or fully opening degree when the internal pressure of the airbag reaches the predetermined value or higher and an occupant contacts the airbag (refer to WO 2008/136336 and JP, A, 2008-308139, for example).